SpudFiles

hi, i want to build a spud gun with a chamber made of 4" pvc 5 feet long, converting to barrel of 2" pvc 10 feet long.....shooting a potato and using hairspray as fuel, how far do you think my potato would go???

Why didnt you just post this in the other topic?
But you still didnt provide enough information. Chamber fan? What are you using for ignition?
But I would expect the potato to go roughly 150-200yards but that is probably overestimating.
There are ballistics calculators out there that would give a more accurate answer.
And I would highly reccomend you cut your chamber down to 2ft and keep your barrel the same...that would give you a nice C:B

bob: his ratio is 1:1.. (i atleast think so)

i think it will get about 300yards if you put some effort into it.

bob: his ratio is 1:1.. (i atleast think so)

4in pipe does not have twice the volume of 2in pipe, it has about 4x the volume.
4in pipe has an ID of 3.998, so 3.998/2=1.999.....1.999*1.999=3.996
3.996*60(in)=239.76*3.14=752.846ci
2in pipe has an ID of 2.049, so 2.049/2=1.0245....1.0245*1.0245=1.0496
1.0496*120(in)=125.952*3.14=395.489ci
which gives a ratio of 1.9:1, not excactly ideal

but shorten that chamber two 2ft and look what happens.
3.996*24(in)=95.904*3.14=301.138ci
And it comes out with a ratio of 0.76:1, ideal

oh dude..
i allways talk before i do the maths

what he can do is make the barrel longer and keep the chamber and get more performance

spudfarm wrote:what he can do is make the barrel longer and keep the chamber and get more performance

Im not sure that he wants a 20ft barrel

i uses it

Doubt its much fun to lugg around though

not that bad if it is of PVC so you can acctualy lift it by your self

just out of curiousity...How heavy is your hybrid barrel(in lb's)?

If he put together a gun with a 5ft 4in chamber and a 20ft 2in barrel it would weight around 100lb's or more. Im thinking cfrehr's gun wont be a handheld

cfrehr wrote:hi, i want to build a spud gun with a chamber made of 4" pvc 5 feet long, converting to barrel of 2" pvc 10 feet long.....shooting a potato and using hairspray as fuel, how far do you think my potato would go???

If you're planning to shoot spuds only, you're wasting your time and materials on such a large gun. If the potato doesn't vaporize, you won't get significantly more distance than if you built a more standard size. Also, if you did use a chamber that big, you should put a fan or 2 in there just to circulate the fuel evenly.

Consider scaling things down to say a 2' chamber and 5' barrel. That's still considered a large gun and it will be much more portable....and you'll get the same distance performance with a potato...and a respectable 1.6:1 c:b ratio.

60 kilograms = 132.277357 pounds


i bet the PVC barrel is lighter than you said

Wow, quite heavy.
I bet it weighs atleast 200lbs with a the chamber and fuel meter and everything attatched though.

And I meant the entire PVC gun put together including the chamber.

ok. but we stop talking about this. i talk to you on msn

bigbob12345 wrote:...
which gives a ratio of 1.9:1, not excactly ideal

but shorten that chamber two 2ft and look what happens.
3.996*24(in)=95.904*3.14=301.138ci
And it comes out with a ratio of 0.76:1, ideal

Yes, and the 0.76 CB gun will probably have a lower muzzle velocity than the 1.9 CB gun, if the spud survives. HGDT says (guessed at some things about the gun) the 1.9 CB gun will have a muzzle velocity of 670 FPS, the 0.76 CB gun 520 FPS.

If you want to increase the performance of the gun it needs a longer barrel. Making the chamber smaller will decrease performance.